(a) Field
This disclosure relates to a rechargeable battery.
(b) Description of the Related Art
A rechargeable battery can be recharged and discharged, unlike a primary battery that is not intended to be recharged. A rechargeable battery with low capacity is often used for a small portable electronic device such as a mobile phone, a laptop computer, and a camcorder, while a rechargeable battery with large capacity is often used as a power source for driving a motor such as for a hybrid vehicle.
Recently, a rechargeable battery has been developed to have large capacity, high power, and high energy density using a non-aqueous electrolyte. It can be used to drive a device, for example, a motor for an electric vehicle requiring a large amount of electric power.
Further, a rechargeable battery with high power is generally formed with a plurality of rechargeable batteries coupled in series or in parallel. This rechargeable battery may be cylindrical or prismatic.
A prismatic rechargeable battery typically includes an electrode assembly having positive and negative electrodes and a separator therebetween, a case having a space for housing it, a cap plate closing and sealing the case and having a terminal hole through which a terminal is inserted, and a terminal inserted into the case and protruded outside of the case.
The electrode assembly needs to be insulated from the case. However, it is difficult to install an insulating film between the electrode assembly and the case. In addition, the insulation film may be torn apart during the installation process. When torn apart, it may cause an internal short circuit, resulting in more critical problems such as explosion of a rechargeable battery and the like.
In some cases, the electrode assembly is prepared by laminating positive and negative electrodes and a separator therebetween and then, spiral-winding them together, and pressing them into a flat jelly-roll. Accordingly, the electrode assembly may have a dumbbell-shaped cross-section with both edges convex.
However, since the flat part of the electrode assembly is relatively thinner than convex parts at the edges, it may not be stably attached to the interface of a supporting part.
As a rechargeable battery is repetitively charged and discharged, the electrode assembly therein is also repetitively expanded and shrunk. When the electrode assembly irregularly repeats expansion and contraction, it may deteriorate performance of the rechargeable battery.
In addition, the electrode assemblies may have a gap during the expansion. The gap may cause interfaces to be not uniform, resultantly deteriorating performance of a rechargeable battery.